Cranes or similar lifting devices are well known and are typically used to lift, lower and move horizontally a variety of materials. Cranes are used in a number of applications, such as in the transport industry for loading and unloading freight, the construction industry for movement of various materials and the manufacturing industry for the assembling of heavy materials. One particular type of crane is a mobile crawler crane, which is a crane mounted on an undercarriage with a set of crawler tracks that provide mobility on uneven ground and improved traction.
In the usual arrangement, the crawler tracks comprise a plurality of links formed together in an endless chain-type fashion with pads formed on the links for engagement with the ground. The multiple pads along the lower run of the endless track in engagement with the ground at any one time provide exceptional traction, while the upper run serves to return the track. Driven sprockets engage the inner surfaces of the links to drive the track along an endless path and thereby provide movement to the vehicle.
While crawler tracks are quite useful when the crane is moving about the job site in a traveling mode, they are not well-suited for use in over-the-road or highway travel from one job site to another. Generally, the crane is normally transported on a tractor trailer from one site to the next. In many cases, over-the-road transport requires removing the entire assembly supporting and driving the crawler tracks from the vehicle to reduce the size and load in order to comply with governmental regulations on maximum vehicle width and possibly placing them on a different tractor trailer altogether to comply with maximum weight restrictions.
Since this operation is costly in terms of efficiency, a significant sought after advantage is of course the ability to complete it quickly such that the construction company can make the most efficient use of their capital equipment. In the past, this and other quick assembly type of features have been a particular focus for design of many types of heavy duty crawler cranes Nevertheless, this is typically a difficult process as most axles and side frames are connected with cap screws, which makes it difficult to assemble and disassemble the axles and side frames due to fit interface between the parts. Once assembled together, there are a number of parts required to hold them together, which makes the assembly and disassembly process time-consuming.
Accordingly, a need is identified for addressing and overcoming the foregoing limitations. Specifically, it would be desirable to form a removable connection between the axles and the frames that allows the frames to be easily removed for transport and easily reassembled once the transport is complete. The connection should allow the axles and the frames to easily mate together with a minimum number of parts and minimal effort from the operator. Furthermore, the configuration should perform well in different environments and as the crane ages and wears. Finally, the axles should be laterally adjustable in an efficient manner with minimal operator intervention.